5.1 Scaffolds potentially may be metallic, ceramic, polymeric, natural, or composite materials. Scaffolds are usually porous to some degree, but may be solid. Scaffolds can range from mechanically rigid to gelatinous and can be either absorbable/degradable or nonresorbable/nondegradable. The scaffold may or may not have a surface treatment. Because of this large breadth of possible starting materials and scaffold constructions, this guide cannot be considered as exhaustive in its listing of potentially applicable tests. A voluntary guidance for the development of tissue-engineered products can be found in Omstead, et al (1).13 Guide F2027 contains a listing of potentially applicable test methods specific to various starting materials. Guidance regarding the evaluation of absorbable polymeric materials and constructs can be found in Guide F2902. Guidance regarding the evaluation of collagen-based materials can be found in Guide F2212. Guidance regarding the evaluation of scaffolds composed of ceramic or mineral based material is available in Guide F2883. Similarly, guidance for the assessment of unique aspects of scaffolds based on hydrogels (for example, gel kinetics, mechanical stability, and mass transport properties) may be found in Guide F2900.

5.2 Each TEMP scaffold product is unique and may require testing not within the scope of this guide or other guidance documents. Users of this guide are encouraged to examine the references listed herein and pertinent FDA or other regulatory guidelines or practices, and conduct a literature search to identify other procedures particularly pertinent for evaluation of their specific scaffold material (2,3,4). It is the ultimate responsibility of the TEMP scaffold designer to determine the appropriate testing, whether or not it is described in this guide.

5.3 A listing of potentially applicable tests for characterizing and analyzing the materials utilized to fabricate the scaffold may be found in Guide F2027. However, conformance of a raw material to this and/or any other compendial standard(s) does not, in itself, ensure that the selected material is suitable or that the provided quality is adequate to meet the needs of a particular application. Thus, other characterization procedures may also be relevant and not covered by this guide.

5.4 The following provides a listing of links to U.S. Food & Drug Administration (FDA)—Center for Devices & Radiologic Health (CDRH) web sites that may potentially contain additional guidance relevant to biomaterial scaffolds covered within this document.

5.4.2.2 This database provides a resource for locating non-binding FDA guidance documents intended for CDRH staff, regulated industry and the public that relate to the processing, content, and evaluation of regulatory submissions, the design, production, manufacturing, and testing of regulated products, and FDA inspection and enforcement procedures.

5.4.2.3 A document within this database possessing content that warrants particular consideration for its potential applicability for tissue engineering scaffolds is Guidance for the Preparation of a Premarket Notification Application for a Surgical Mesh; Final.

1.1 This guide is a resource of currently available test methods for the characterization of the compositional and structural aspects of biomaterial scaffolds used to develop and manufacture tissue-engineered medical products (TEMPs).

1.2 The test methods contained herein guide characterization of the bulk physical, chemical, mechanical, and surface properties of a scaffold construct. Such properties may be important for the success of a TEMP, especially if they affect cell retention, activity and organization, the delivery of bioactive agents, or the biocompatibility and bioactivity within the final product.

1.3 This guide may be used in the selection of appropriate test methods for the generation of an original equipment manufacture (OEM) specification. This guide also may be used to characterize the scaffold component of a finished medical product.

1.4 This guide is intended to be utilized in conjunction with appropriate characterization(s) and evaluation(s) of any raw or starting material(s) utilized in the fabrication of the scaffold, such as described in Guide F2027.

1.5 This guide addresses natural, synthetic, or combination scaffold materials with or without bioactive agents or biological activity. This guide does not address the characterization or release profiles of any biomolecules, cells, drugs, or bioactive agents that are used in combination with the scaffold. A determination of the suitability of a particular starting material and/or finished scaffold structure to a specific cell type and/or tissue engineering application is essential, but will require additional in vitro and/or in vivo evaluations considered to be outside the scope of this guide.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.